The present invention generally relates to ballistic projectiles. The invention particularly relates to bullets capable of transitioning from lethal to less lethal or nonlethal after the bullet travels a distance or period of time after being fired (propelled) from a firearm.
Conventional cartridge ammunition comprise a cartridge casing, a projectile (bullet), and a propellant charge within the casing that expels the bullet from the casing. Current bullets for firearms are made of a variety of materials depending on their intended application. The most common bullet material is lead, which has a combination of low hardness, low cost, and high density, making it a practical material for most bullet applications. FIGS. 1 and 2 are plots representing hardness vs. density and price vs. density, respectively, for a variety of common bullet materials. A bullet formed of a material having relatively low hardness, such as lead, promotes deformation of the bullet upon impact, thereby transferring a greater amount of energy to its target than a bullet formed of a material having a higher hardness. In contrast, if piercing is desired, the bullet may be formed of a material having relatively high hardness, such as tungsten or depleted uranium, or may include a jacket encasing the low hardness material, called a full metal jacket, commonly formed of copper, copper alloys, or certain grades of steel. High density materials are preferred to maximize the momentum and kinetic energy of a bullet, which results in improved accuracy and stopping power. If toxicity is a concern, materials such as copper-tin alloys or bismuth may be practical alternatives to more toxic materials, such as lead. Standard bullets are commonly produced either by an extrusion and pressing process or by a casting process. For example, in mass production, a lead billet can be extruded into lead wire, which is cut into sections and pressed into a bullet-like shape to form a lead bullet. Casting processes are more typically used to produce small batches of bullets.
Standard bullets, generally comprising a solid body formed of a high-density material such as those identified in FIGS. 1 and 2, retain a significant portion of their energy after traveling hundreds or even thousands of meters. Consequently, there is a risk for unintended and collateral damage because bullets may maintain lethality until they reach their maximum range or impact a person or object (which raises the risk of shrapnel). There is a particular concern for unintended death or injury of bystanders and collateral damage when a target is missed. Hence, there is a definitive need in the law enforcement, military, and civilian sectors for a bullet that is capable of significantly reducing unintended damage, which would enable police officers, soldiers, and citizens to more confidently and safely wield their firearms offensively, defensively, and recreationally.
Several solutions have been proposed that render bullets non-lethal or less lethal. These solutions include frangible bullets, self-destructing bullets, and non-lethal alternatives such as rubber or plastic bullets.
Frangible bullets are configured to break apart upon impact and are therefore intended to reduce the likelihood that the bullet will penetrate or damage a wall, building, or the like. There are multiple types of frangible ammunition. One type includes a bullet formed of a sintered metal powder. As these bullets are not a solid piece of metal, and instead contain porosity or cavities, they are more likely to disintegrate upon impact with a solid object, and less likely to travel through objects, such as thick drywall or wood, depending on the bullet design. Ammunition of this type is disclosed in U.S. Pat. No. 8,225,718 to Joys et al., the contents of which are incorporated herein in its entirety.
A second type of frangible bullets is similar to hollow point ammunition (a standard type of bullet with a hollowed out tip that deforms easier in order to impart more energy to the target), but with the head of the bullet full of pellet shot instead of being hollow. For example, the bullet may include a scored jacket with a plastic tip, securing compressed shot within the jacket. Upon impact the plastic tip is forced rearward into the bullet, causing the jacket to fracture along the score marks and release the compressed shot therein. Release of the shot disperses the mass of the bullet, allowing it to transfer its energy quickly and thus reducing the likelihood that it will pierce through walls.
U.S. Patent Application Publication No. 2002/0152914 to Cox discloses a self-destructing bullet that comprises a body portion having a leading end, a base portion spaced apart from the leading end, and a hollow chamber defined within the body intermediate the leading end and base portions thereof. The body of the bullet is formed of a low temperature melting point metallic material. A catalyst, comprised of a high temperature combustible material, is positioned within the hollow chamber of the bullet. A combustible fuse extends from the base portion of the bullet to engage the catalyst. When assembled in a cartridge and fired from a firearm, the propellant charge of the cartridge will ignite the fuse of the self-destructing bullet. After the bullet has traveled for a predetermined period of time the fuse ignites the catalyst, and once ignited, the catalyst in turn combusts and melts or consumes the metallic material which comprises the body of the bullet to accomplish the self-destruction of the bullet.
While the above-noted types of bullets represent advances in non-lethal or less-lethal ammunition, improvements are still necessary. For example, though frangible bullets may reduce or even eliminate the potential for creating shrapnel, they must collide with an object in order to fragment. Prior to impact with an object, the bullets can maintain their lethality during travel (flight) similar to standard bullets, creating the possibility of hitting bystanders. Self-destructing bullets commonly disintegrate by explosion giving rise to shrapnel, whose momentum, size and shape can still inflict significant damage or death on unintended bystanders or collateral damage. Nonlethal alternatives such as rubber or plastic bullets do not contain the stopping power police force need to take down an intended target and they are designed to impact in the same fashion as standard lethal bullets, albeit with lesser momentum and less harmfully.
In view of the above, there is an ongoing desire for bullets having the stopping power and lethality of standard bullets, the shrapnel-eliminating benefits of frangible bullets, and the capability for reducing the risk of collateral damage and bystander injury or death.